The present invention relates to a ceramic filter and a method of regenerating the filter. More particularly, it relates to a ceramic filter formed with reduced membrane formation times and having a high water permeation performance and a high separation performance, and a method of regenerating the filter.
Heretofore, various methods of forming an inorganic separation membrane on a porous base member have been known. For example, a hot coating process is known (see Non-Patent Document 1). This is a method of rubbing a tube base member with cloth containing a silica sol to apply the sol, thereby forming the inorganic separation membrane on an outer surface of the heated tube base member.
A method of forming the inorganic separation membrane on an inner surface of a porous base member having a tubular shape or a cylindrical lotus-root-like monolith shape by filtering membrane formation is also known (see Patent Document 1). The outer surface of the porous base member is held at a pressure lower than that of an inner surface thereof which comes in contact with a sol liquid to form the membrane on the inner surface of the porous base member.
On the other hand, examples of a separation membrane having excellent thermal resistance and stability include a carbonaceous membrane, and the carbonaceous membrane formed on the porous base member is known.
[Patent Document 1] Japanese Patent Application Laid-Open No. 2006-212480
[Non-Patent Document 1] Separation and Purification Technology 25 (2001) 151 to 159
As the inorganic separation membrane, for example, a silica membrane has a high permeability and a high separability, but in order to form the silica membrane as the separation membrane on the porous base member, four or five types of silica sols having different particle diameters have to be formed into membranes several times, respectively, membrane formation is performed ten or more times in total, and this increases manufacturing costs.
On the other hand, when the carbonaceous membrane is formed on the porous base member, a coating liquid having the same composition may be formed into membranes about several times, the membrane can inexpensively be manufactured, but the permeation performance of the carbonaceous membrane is inferior to that of an inorganic separation membrane such as the silica membrane.